1. Field of the Invention
The invention relates to a device for resetting opposite guide segments of a continuous casting or continuous casting and rolling plant in three different positions, with the device including a hydraulic cylinder connectable with one of the opposite guide segments, a double-acting piston connectable with another of the opposite guide segments and displaceable in the hydraulic cylinder between three positions corresponding to the three different positions of the guide segments and of which three piston positions one position is defined by a stop surface provided inside of the hydraulic cylinder.
2. Description of the Prior Art
European Patent Publication No. EP 0 545 104 B1 discloses a method of and an apparatus for continuous casting of slabs and ingots in a continuous casting plant with a soft-reduction-line, where the plant includes separate rolls replaceable, separately or as segments, by hydraulic cylinders and having the gap there-between or the distance therebetween steplessly adjustable with spindles. The spindles are displaced by a suitable hydraulic system. However, the spindle displacing or adjusting system is expensive and prone to malfunction.
German Publication DE 195 11 113.2 discloses a billet guide system of a plant for continuous casting of thin slabs wherein the guide rollers are supported in separate frames which are biased against stop surfaces by tie rods. For adjusting the guide system by using mechanically preloaded, with tie rods, frames, with which in a simple manner, the guide rollers, which are supported in the frames, can be properly aligned during the casting process, there is provided, between the stop surfaces for the frames, a hydraulic cylinder operating the tie rods. The misalignment of the guide rolls leads to the deviation of the thickness of the slab. Also, the guide system is adjusted in order to compensate for non-uniform thermal expansion of the rollers and for their wear. The spacing between the frames is adjusted steplessly. However, a small adjustment range significantly limits the use of the method and device disclosed in DE 195 11 113.2.
German Publication No. DE 43 06 853 A1 discloses a guide system for a continuous casting plant for producing slab, in particularly, by the method of continuous casting and rolling. To produce slabs having different thicknesses, paired opposite rolls are supported in frames or stand parts connected by tie rods with a piston-cylinder unit. The power flux of the piston-cylinder unit is adjusted by providing spacers between upper and lower frame parts. In order to be able to reset the guide rollers in three definite positions, in particular during the casting and rolling of thin slabs, and in particular in the solidification region, a hydraulic annular cylinder unit is provided between the cylinder of the piston-cylinder unit and the spacers. The annular cylinder unit surrounds the piston rod, with the annular or ring-shaped piston caps the annular cylinder unit carrying the spacers.
DE 43 06 853 A1 contemplates serial connection of the hydraulic cylinders used for operating the billet guiding means which require resetting or adjustment of more than two positions. The drawback of the proposed solution consists in that one or more positions are defined by stops formed in the cylinder. The changes of the reset positions can be effected only with substantial expenses as they require modification of the hydraulic cylinders themselves. The modification of the cylinders is time-consuming and results in putting, e.g., the guide segments of a continuous casting plant out of service for a long time. This requires an availability of a large number of replacement segments. In addition, this arrangement requires the use of two hydraulic cylinders arranged one after another, with two sealing elements for each piston rod. In addition, a tedious adjustment of the spacers is involved.
Accordingly, an object of the present invention is to provide a device which would insure an easy and simple adjustment of the distance between opposite segments of a continuous casting or casting and rolling plant.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a device in which the three positions are defined by stop surfaces associated with the hydraulic cylinder with at least one stop surface being provided outside of the hydraulic cylinder. By associating the stop surfaces with the hydraulic cylinder, the structure of the device is simplified, and arrangement of at least one stop surface outside of the hydraulic cylinder provides for an easy access thereto and for its easy adjustment.
In accordance with advantageous embodiment of the present invention, the hydraulic cylinder is arranged on an outer side of one of the opposite guide segments, and the piston has a first piston rod provided on one of its sides and connectable to another of the opposite guide segments. The piston rod projects from a cylinder end at which the cylinder is connectable with the one of the opposite guide segments. Such an arrangement insures an easy access to the hydraulic cylinder. In addition, there is space at the free end of the hydraulic cylinder for outer stop surfaces and stops.
Advantageously, the hydraulic cylinder has first and second end walls defining two, first and second, inner stop surfaces, respectively, which define two positions of the piston, with the first end wall having a flange or a pivot lug for connecting the hydraulic cylinder with the one of the opposite guide segments.
Providing a multi-functional end surface, which closes the cylinder chamber, serves as a guide for the first piston rod, and defines an inner stop surface for the piston, reduces the manufacturing costs.
Securing of the hydraulic cylinder at its side through which the first piston rod projects, provides for attachment of a second piston rod to another side of the piston, with the second piston rod extending through a guide bore formed in the second end wall and carrying at its free end a first outer stop. This insures an easy access to the first outer stop.
According to a further advantageous embodiment of the present invention, the hydraulic cylinder has a cylindrical extension, and an annular piston, which defines a first outer stop surface for the first outer stop, is displaceably arranged in the hydraulic extension. The annular piston is displaceable along the second piston rod. The displaceability of the annular piston makes it suitable for defining a middle position of the piston because it is subjected to overpressure when the pressure is insufficient for the main piston to reach its inner position.
The operational position of the annular piston is defined by a collar provided on an inner circumference of the cylindrical extension and which cooperates with a shoulder provided an outer circumference of the annular piston for limiting an outward stroke of the annular piston.
The three positions of the piston are determined by application of pressure to opposite sides of the and one side of the annular piston.
In accordance with a further advantageous embodiment of the invention, the second inner stop surface is replaced by a second outer stop surface for a second outer stop formed by a free end surface of the second piston rod. The second outer stop surface is defined by a pot-shaped member releasably connected with the cylindrical extension. This insures an easy access to two stops and two stop surfaces and an easy adjustment of the positions of at least first stop and a second stop surface.
The adjustment of the positions of the first stop and the second stop surface by using spacers of different thicknesses permits to achieve precise positioning of the first stop and the second stop surface can be achieved.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.